In 1976, Drasin gave a complete solution to the inverse problem of Nevanlinna theory (value distribution theory),[2] which was posed by Rolf Nevanlinna in 1929.[3] In the 1930s, the problem was investigated by Nevanlinna and by, among others, Egon Ullrich(de) (1902–1957) with later investigations by Oswald Teichmüller (1913–1943), Hans Wittich, Le Van Thiem (1918–1991) and other mathematicians. Anatolii Goldberg (1930–2008) was the first to completely solve the inverse problem in the special case where the number of exceptional values is finite.[4] For entire functions the problem was solved in 1962 by Wolfgang Fuchs and Walter Hayman.[5] The general problem concerns the question of the existence of a meromorphic function at given values of the exceptional values and associated deficiency values and branching values (with constraints from the Nevanlinna theory). Drasin proved that there is a positive answer to Nevanlinna's problem.[6]
In 1994 Drasin was an Invited Speaker at the ICM in Zurich.[7] Since 1996 he is a co-editor of the Annals of the Finnish Academy of Sciences and a co-editor of Computational Methods in Function Theory. He was a co-editor of the American Mathematical Monthly from 1968 to 1971. From 2002 to 2004 he was a program director/analyst for the National Science Foundation.
with Daniel F. Shea: Asymptotic properties of entire functions extremal for the theorem. Bull. Amer. Math. Soc. 75 (1969) 119–122. doi:10.1090/S0002-9904-1969-12169-5
with Daniel F. Shea: Pólya peaks and the oscillation of positive functions. Proc. Amer. Math. Soc. 34 (1972) 403–411. doi:10.1090/S0002-9939-1972-0294580-X
A meromorphic function with assigned Nevanlinna deficiencies. Bull. Amer. Math. Soc. 80 (1974) 766–768. doi:10.1090/S0002-9904-1974-13595-0
with Guang Hou Zhang, Lo Yang, and Allen Weitsman. Deficient values of entire functions and their derivatives. Proc. Amer. Math. Soc. 82 (1981) 607–612. doi:10.1090/S0002-9939-1981-0614887-9
"Proof of a conjecture of F. Nevanlinna concerning functions which have deficiency sum two." Acta Mathematica 158, no. 1 (1987): 1–94. doi:10.1007/BF02392256
with Pekka Pannka: "Sharpness of Rickman’s Picard theorem in all dimensions." Acta Mathematica 214, no. 2 (2015): 209–306. doi:10.1007/s11511-015-0125-x
^Drasin The inverse problem of the Nevanlinna theory , Acta Mathematica Vol. 138, 1976, pp. 83–151, doi:10.1007/BF02392314. Updated in: Drasin On Nevanlinna's Inverse Problem , Complex Variables, Theory and Application, Vol. 37, 1998, pp. 123–143 doi:10.1080/17476939808815127
^Nevanlinna Le théorème de Picard-Borel et la théorie des fonctions méromorphes, Gauthier-Villars 1929. Nevanlinna also solved a special case.
^Drasin, David. "Meromorphic functions: progress and problems." In Proceedings of the International Congress of Mathematicians, pp. 828–835. Birkhäuser Basel, 1995. doi:10.1007/978-3-0348-9078-6_12